"Republicans in Congress continue to oppose serious efforts to create jobs, grow the economy, and level the playing field for working families," President Barack Obama, a Democrat, said in a statement.

"That's wrong, and it's harmful for our national efforts to rebuild an economy that gives every American who works hard a fair shot to get ahead."

The bill needed 60 votes to proceed to a final up-or-down vote for passage. It failed 53-44, with Senate Democratic Majority Harry Reid changing his vote from yes to no at the last minute in a procedural manoeuvre enabling him to bring the bill up for debate again.

'Good politics'

The bill would have barred employers from retaliating against employees who share salary information and limited the factors businesses can cite for paying women less than men.

But Republicans have argued that would increase frivolous lawsuits against companies.

"It's time for Washington Democrats to stop protecting trial lawyers and start focusing on actually helping the people we were sent here to represent," Republican Senate Minority Leader Mitch McConnell said.

Conservatives have rejected similar legislation in the upper chamber of Congress in 2010 and 2012.

The bill's failure came a day after Mr Obama issued two executive orders aimed at reducing gender disparities in government workforce pay.

The bill was the latest battle waged by the political parties to attract crucial women voters as they approach the mid-term elections in November.

Those elections will determine which party controls the US Senate and House of Representatives for the final two years of Mr Obama's presidential term.